The present invention relates to a control valve for a variable capacity compressor, which is adapted for use in controlling the capacity of variable capacity compressor to be employed in air conditioners for vehicles, etc., and in particular to an electromagnetic controlling means-attached control valve for a variable capacity compressor, which is provided with a pressure sensitive bellows and a solenoid magnetizing means.
As a variable capacity compressor to be employed in air conditioners for vehicles, etc., there is known a wobble plate type variable capacity compressor which is designed to change the discharge capacity thereof by making the inclination angle of the wobble plate variable, thereby controlling the pressure of crankcase of the wobble plate type variable capacity compressor. Namely, this control valve for a variable capacity compressor functions as a flow rate controlling valve for controlling the pressure of crankcase by introducing a discharge pressure into the crankcase of the wobble plate type variable capacity compressor.
As one example of a control valve for a variable capacity compressor, there is known, as shown in Japanese Patent Unexamined Publication (Kokai) H9-268974, an electromagnetic controlling means-attached control valve for a variable capacity compressor, which comprises a valve housing having a valve port formed between an inlet port and an outlet port, a valve disposed inside the valve housing for controlling the flow rate through the adjustment of opening degree of the valve port, a pressure sensitive bellows for actuating the opening or closing of the valve, and a solenoid magnetization means.
This electromagnetic controlling means-attached control valve for a variable capacity compressor is basically designed such that through a detection of an inlet pressure of the compressor, the pressure sensitive bellows is extended or contracted to actuate the valve so as to adjust the opening degree of the valve port, thereby controlling the pressure of crankcase in accordance with the magnitude of inlet pressure. Therefore, when a cooling load is relatively large, the valve is caused to deviate in the direction to close the valve through the magnetization of the solenoid magnetizing means, thereby decreasing the opening degree of the valve port and hence, making the pressure of crankcase close to the inlet pressure, thus controlling the variable capacity compressor to increase the discharge capacity thereof.
Although the aforementioned electromagnetic controlling means-attached control valve for a variable capacity compressor is capable of achieving objects expected, the pressure sensitive bellows and solenoid magnetization means thereof are arranged in a row along the direction of opening or closing the valve, thus raising a problem that the size of the compressor becomes bulky, i.e. it is difficult to make the compressor compact in configuration. The miniaturization of the control valve for a variable capacity compressor is very important requisite as it is mounted on a vehicle.
Further, the conventional electromagnetic controlling means-attached control valve for a variable capacity compressor is constructed such that a solenoid assembly (electromagnetic coil portion) constituting an electric component of the solenoid magnetization means is mounted on the valve housing by means of caulking, i.e. the solenoid assembly is not enabled to be reattached afterward to the valve housing. Therefore, the conventional electromagnetic controlling means-attached control valve is poor in operability in assembling the solenoid assembly, i.e. it is impossible to easily perform the exchange of the solenoid assembly as demanded for meeting the property of the control valve, or for the purpose of maintenance.
The present invention has been made under the circumstances mentioned above, and therefore an object of the present invention is to provide an electromagnetic controlling means-attached control valve for a variable capacity compressor, which is suited for miniaturizing the valve, for enabling the solenoid assembly to be reattached afterward to the valve housing, and for the attachment or exchange of the solenoid assembly.
With a view to achieve the aforementioned object, the present invention provides a control valve for a variable capacity compressor, which comprises a valve housing having a valve port formed between an inlet port and an outlet port, a valve disposed inside the valve housing for controlling the flow rate through the adjustment of opening degree of the valve port, a pressure sensitive bellows for actuating the opening or closing of the valve, and a solenoid magnetization means; which is featured in that the solenoid magnetization means comprises a solenoid assembly, a fixed suction member, a plunger which is designed to be adsorbed onto the fixed suction member by the magnetization of solenoid assembly, and a plunger spring for urging the plunger to move in a direction away from the fixed suction member; that the plunger is provided therein with an inner cylindrical portion housing therein the pressure sensitive bellows and connected at the distal end portion thereof with the valve, the pressure sensitive bellows being housed inside the inner cylindrical portion; and that the pressure sensitive bellows is fixedly connected through one end member thereof with a distal end of the plunger and through the other end member thereof with the fixed suction member.
According to a preferable embodiment of the control valve for a variable capacity compressor of the present invention, the control valve further comprises an adjuster plug screwed to the fixed suction member, and said other end member of the pressure sensitive bellows is connected via a connecting rod with the adjuster plug, thereby enabling to adjust the initial state of the pressure sensitive bellows by means of the adjuster plug.
According to another preferable embodiment of the control valve for a variable capacity compressor of the present invention, a valve-closing spring-for urging the valve in the direction to close the valve is interposed between the valve and an adjusting spring retainer screwed to the valve housing thereby enabling to adjust the set load of the valve-closing spring by means of the adjusting spring retainer, or a valve-closing spring for urging the valve in the direction to close the valve is interposed between the valve and a press-fitted spring retainer press-fittingly fixed to the valve housing, the fixed position thereof being made adjustable, thereby enabling to adjust the set load of the valve-closing spring by means of the press-fitted spring retainer.
According to a further preferable embodiment of the control valve for a variable capacity compressor of the present invention, the valve is constituted by a spool valve or a ball valve.
According to a further preferable embodiment of the control valve for a variable capacity compressor of the present invention, it is featured in that it further comprises a plunger tube fixedly attached to the solenoid-mounting portion of the valve housing and housing therein the plunger which is made slidable in the axial direction thereof, that the fixed suction member is coaxially fixed to the distal end of the plunger tube, and that the cylindrical solenoid assembly is removably mounted on the outer wall of the plunger tube and of the fixed suction member.
According to the control valve for a variable capacity compressor of the present invention which is constructed as mentioned above, the pressure sensitive bellows is housed in an inner cylindrical portion of the plunger, i.e. the pressure sensitive bellows is housed inside the plunger, thereby making it possible to miniaturize the control valve.
Further, according to the control valve for a variable capacity compressor of the present invention, the initial state of the pressure sensitive bellows is made adjustable by means of the adjuster plug, and the set load of the valve-closing spring is made adjustable by means of the adjusting spring retainer or by means of the press-fitted spring retainer.
Moreover, according to the control valve for a variable capacity compressor of the present invention, since the cylindrical solenoid assembly is removably mounted on the outer wall of the plunger tube and of the fixed suction member, the solenoid assembly can be reattached afterward to the valve housing, thereby making it possible to easily perform the attachment or exchange of the solenoid assembly.